package io.netty.example.splicing.delimiter;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;

import java.net.InetSocketAddress;

/**
 * 类说明：使用自定义分隔符解决 粘包/半包问题
 */
public class DelimiterEchoServer {
  
  public static final String DELIMITER_SYMBOL = "@~";
  public static final int PORT = 9997;
  
  public static void main(String[] args) throws InterruptedException {
    DelimiterEchoServer delimiterEchoServer = new DelimiterEchoServer();
    System.out.println("服务器即将启动");
    delimiterEchoServer.start();
  }
  
  public void start() throws InterruptedException {
    // 这里是 主从模式
    // boss/ worker
    EventLoopGroup bossGroup = new NioEventLoopGroup(1);
    
    try {
      ServerBootstrap b = new ServerBootstrap();/*服务端启动必须*/
      b.group(bossGroup)/*将线程组传入*/
          // 从这里 指定 IO 的网络传输
          .channel(NioServerSocketChannel.class)/*指定使用NIO进行网络传输*/
          .localAddress(new InetSocketAddress(PORT))/*指定服务器监听端口*/
          /*服务端每接收到一个连接请求，就会新启一个socket通信，也就是channel，
          所以下面这段代码的作用就是为这个子channel增加handle*/
          .childHandler(new ChannelInitializerImp());
      ChannelFuture f = b.bind().sync();/*异步绑定到服务器，sync()会阻塞直到完成*/
      System.out.println("服务器启动完成，等待客户端的连接和数据.....");
      f.channel().closeFuture().sync();/*阻塞直到服务器的channel关闭*/
    } finally {
      bossGroup.shutdownGracefully().sync();/*优雅关闭线程组*/
    }
  }
  
  // 继承了 channel init 类
  private static class ChannelInitializerImp extends ChannelInitializer<Channel> {
    
    @Override
    protected void initChannel(Channel ch) throws Exception {
      ByteBuf delimiter = Unpooled.copiedBuffer(DELIMITER_SYMBOL.getBytes());
      ch.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, delimiter));
      ch.pipeline().addLast(new DelimiterServerHandler());
    }
  }
  
}
